Magnetoresistance effect device, method of manufacturing the same, magnetic memory apparatus, personal digital assistance, and magnetic reproducing head, and magnetic information reproducing apparatus

ABSTRACT

Magnetoresistance effect devices for attaining magnetically stability and for reducing a switching magnetic field. One of the ferromagnetic layers of the magnetoresistance effect device has a plane shape in which a width of an end portions is wider than a center portion sandwiched by two end portions. The end portions are not symmetrical with respect to an easy magnetization axis or longer axis of the plane shape of ferromagnetic material layer, but are substantially rotationally symmetrical with a center of the plane shape as a pivot. The plane shape may have an S-shape where its magnetic domain is stabilized and the switching magnetic field is reduced. The manufacturing method uses two linear mask patterns intersecting with each other to form sharp corners of a ferromagnetic tunnel junction. An electron beam (EB) drawing may be used to form the S-shape plane. The magnetoresistance effect devices may be used in a magnetic memory apparatus, such as a random access memory, a personal digital assistance, a magnetic reproducing head, and a magnetic information reproducing apparatus.

CROSS REFERENCE TO A RELATED APPLICATION

[0001] This application claims the benefit of priority from JapanesePatent Application No. 2001-076614, filed on Mar. 16, 2001, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the invention

[0003] The present invention relates to a magnetoresistance effectdevice, a method of manufacturing the same, a magnetic memory apparatus,a personal digital assistance, a magnetic reproducing head and amagnetic information reproducing apparatus.

[0004] 2. Discussion of the Background

[0005] Solid magnetic memories including a Magnetic Random Access Memory(MRAM) using a MagnetoResistance (MR) effect element have been proposed.Further, a Tunnel MagnetoResistance effect device (TMR device) that usesa ferromagnetic tunnel junction has recently drawn attention as acomponent of a memory cell of the MRAM.

[0006] A conventional ferromagnetic tunnel junction has a three-layeredfilm including a first ferromagnetic metal layer, a nonmagneticdielectric layer and a second ferromagnetic metal layer. A current forsensing the tunnel junction's resistance flows from the first to thesecond of the ferromagnetic material layers via the nonmagneticdielectric layer. The nonmagnetic dielectric layer forms a tunneljunction of the device, sometimes referred to as a tunnel dielectriclayer. Each of the two ferromagnetic layers has a magnetizationdirection and a resistance value of the tunnel junction that changes inproportion to a cosine of a relative angle of magnetization directionsof the first and second ferromagnetic layers.

[0007] The resistance value is at a minimum value when two magnetizationdirections of the ferromagnetic layers are parallel to each other and isa maximum value when the magnetization directions are not parallel toeach other. A change in a resistance value (resistance amplitude) of theTMR device as much as 49.7% at room temperature (Appl. Phys. Lett.77,283 (2000)) has been reported.

[0008] The magnetization of one of the ferromagnetic layers of theferromagnetic tunnel junction is fixed or pinned so the magnetizationdoes not change or is inverted in an applied magnetic field, whereby thefixed magnetization ferromagnetic layer is used as a reference layer.The magnetization of the other ferromagnetic material layer is set to befree to rotate in the specific magnetic field, whereby the freemagnetization ferromagnetic layer is used as a memory layer.

[0009] Several methods for fixing the magnetization of the referencelayer and for allowing the magnetization free to rotate in the memorylayer are disclosed in U.S. Pat. No. 5,159,513, the entire content ofwhich is incorporated by reference.

[0010] In addition, the magnetization direction of the memory layer ischanged in an applied magnetic field and the memory layer retains thechanged magnetization direction. Further, the magnetization direction ofthe reference layer does not change in the applied magnetic field. Thus,the relative angle (i.e., parallel or antiparallel) of themagnetizations between the reference layer and the memory layer ischanged. A binary value of “0” or “1” can be denoted to correspond toeach of the parallel or antiparallel states.

[0011] Further, the magnetic information is written or recorded byinverting or changing the magnetization of the memory layer by theapplied magnetic field. This is accomplished by generating a current toflow through a write line, which is electrically separate from but nearthe memory cell. The written or recorded information is read orreproduced by detecting a tunnel resistance change from a sense currentflowing through the ferromagnetic tunnel junction. Further, a magneticmemory apparatus includes a number of the memory cells usually alignedin column and row directions on a same base, such as a semiconductorsubstrate.

[0012] A switching transistor may also be arranged with each memory celland be coupled to the TMR device, similar to the Dynamic Random AccessMemory (DRAM). Thus, an integrated peripheral circuit may select anarbitrary memory cell of the memory array. In addition, a diode can beused instead of the switching transistor and be placed at anintersection of a word line and a bit line (see U.S. Pat. Nos. 5,640,343and 5,650,958, for example), where either the word line or the bit lineis coupled to the TMR device via the diode, and the other of the wordline or the bit line is directly coupled to the TMR device.

[0013] To form a highly integrated memory apparatus, a size of thememory cell including the TMR device should be reduced. However, as thesize of ferromagnetic layer of the TMR device is reduced, a coerciveforce of the reduced ferromagnetic material layer becomes larger. Amagnitude of a coercive force corresponds and is proportional to amagnitude of a switching magnetic field necessary for inverting amagnetization of the ferromagnetic memory layer. Therefore, an increaseof the coercive force signifies an increase in the writing current,resulting in an increase in power consumption. An important subject tosolve is to build the highly integrated magnetic memory apparatus with areduction in coercive force of each ferromagnetic memory layer.

[0014] The TMR device usually has a rectangular plane shape, however, itis known that magnetic edge domains are produced in a small rectangularshape ferromagnetic layer (J. App. Phys. 81,5471 (1997)). The magneticedge domain is formed, because magnetization at two shorter sides of therectangular shape forms a pattern spirally rotated in line with the sideto reduce a demagnetizing field energy.

[0015] For example, FIG. 1A is a plan view of an example of such amagnetic structure. As shown, the magnetic structure is an S-shapedmagnetic domain structure, in which a magnetization at a center 11 isproduced in a direction parallel to a magnetic anisotropy. Further, edgemagnetic domains at both end portions 12 and 13 are produced and have amagnetization in a direction different from the center 11. FIG. 1B is aplan view of a C-shaped magnetic domain structure, in which the center11 and both end portions 14 and 15 have different magnetizationdirections and in which the magnetizations of the end portions 14 and 15are antiparallel to each other.

[0016] When the magnetization of the rectangular-shaped ferromagneticmemory layer starts to change or invert, each of the edge domains areasspreads. When the edge domains have magnetization directionsantiparallel to each other as shown in FIG. 1B, a domain wall surroundsthe center of the ferromagnetic material memory layer, whereby thecoercive force of the memory layer is increased.

[0017] In addition, a ferromagnetic memory layer having an ellipticshape for reducing the edge domains is disclosed in U.S. Pat. No.5,757,695. The elliptic-shaped ferromagnetic memory layer is formed toreduce a production of the edge domains and to promote a single magneticdomain in the entire layer, whereby a magnetization can be uniformlyinverted over the entire ferromagnetic memory layer and an inversionmagnetic field is reduced.

[0018] A ferromagnetic layer having a shape of a parallelogram has beenproposed as a memory layer (see Japanese Patent Laid-Open No. H11-273337). In this case, although edge domains are present, the edgedomains do not extend over a large area as in the case of a rectangularshape, and formation of very small domains during magnetizationinversion is prevented. Therefore, magnetization of the memory layer canbe inverted substantially uniformly. As a result, the inversion magneticfield can be reduced.

[0019] As a method of preventing a change of the complicated magneticstructure, magnetically fixing edge domains of the memory layer has beenexamined (see U.S. Pat. No. 5,748,524 and Japanese Patent Laid-Open No.2000-100153).

[0020] Further, a tri-layered film including two ferromagnetic layersand a nonmagnetic layer interposed therebetween is also introduced as amemory layer for reducing an inversion magnetic field. The tri-layeredfilm includes antiferromagnetic coupling between the two ferromagneticlayers and its magnetization as a whole is relatively lower than asingle memory layer having a same shape (see Japanese Patent Laid-OpenNo. H9-25162, Japanese Patent Application No. H9-263741 and U.S. Pat.No. 5,953,248). The two ferromagnetic layers of the tri-layered film aredifferent in magnetic moments or in their film thickness. Further, themagnetizations of two layers are in antiparallel directions byantiferromagnetic coupling, whereby larger portions of the twomagnetizations are effectively cancelled and the tri-layered film as thememory layer is substantially equivalent to a single ferromagnetic layerhaving a small amount of magnetization in easy magnetization axisdirection.

[0021] When a magnetic field in a direction inverse to the direction ofthe easy magnetization axis is provided to the tri-layered memory film,each magnetization of the respective ferromagnetic layers is inverted orchanges while maintaining antiferromagnetic coupling. Magnetic forcelines of the multi-layered film is closed in the tri-layered film andthe influence of a demagnetizing field is inconsiderable, whereby aswitching magnetic field of the memory film is determined by adifference of coercive forces between the two ferromagnetic layers, andthe switching magnetic field for the multi-layered film is reduced.

[0022] Some methods for manufacturing the highly integrated MRAM havingmemory cells of a submicron size have been researched and method ofusing an electron beam (EB) drawing for making patterns of the memorycells is described in a journal, W. J. Gallagher et al., J.Appl. Phys.81,3741 (1997).

SUMMARY OF THE INVENTION

[0023] As described above, reducing a switching magnetic field forinverting or changing magnetization of a memory layer/film of a magneticmemory cell is an indispensable factor and tri-layered films in which anantiferromagnetic coupling exists in two ferromagnetic material layersis proposed.

[0024] However, when a width of a shorter side of a small ferromagneticlayer is equal to or smaller than about several microns to submicrons,magnetic edge domains at two ends portions different from a magneticcenter domain appear under an influence of a demagnetizing field. Inregard to the manufacturing method of the TMR device using an EBdrawing, back scattering of EB at a surface of metal layer, such asferromagnetic layers and nonmagnetic material layer, is stronger than asemiconductor material layer, a known proximity effect of considerablywidening a provided drawing pattern becomes significant, wherebyfineness and controllability of a drawn pattern shape is lost.

[0025] As a result, even when a rectangle is intended to be drawn as ashape of a ferromagnetic tunnel junction, the resultant shape lackssharpness at each of the corners. There is a close relationship betweena plane shape of a ferromagnetic tunnel junction of a TMR device andcoercive force (Hc) of the ferromagnetic memory layer of the TMR device.Further, a coercive force of ferromagnetic memory layer having roundedcorners is about twice as much as the ferromagnetic memory layer havinga rectangular shape with sharp corners.

[0026] Accordingly, one object of present invention is to provide a cellhaving a stable magnetic structure in a very small magnetic memory cellto the degree capable of being highly integrated as described above and,at the same time, to reduce a switching magnetic field necessary forwriting information to the cell.

[0027] Another object of present invention is to use the magnetic memorycell of the stable magnetic structure and the low switching magneticfield in a magnetic memory apparatus, such as nonvolatile and randomaccess memories.

[0028] Yet another object of present invention to provide a simplehighly productive manufacturing method for a magnetoresistance effectdevice.

[0029] These and other objects are achieved by providing a novelmagnetoresistance effect device including a first ferromagnetic layer, afirst nonmagnetic dielectric layer formed on the first ferromagneticlayer, and a second ferromagnetic layer formed on the first nonmagneticdielectric layer. Further, one of the first and second ferromagneticmaterial layers includes a plane shape in which a center region isdisposed between first and second end regions, and the center region hasa width narrower than each width of the first and second end regions. Anovel manufacturing method is also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] A more complete appreciation of the present invention and many ofthe attendant advantages thereof is readily obtained as the statebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0031]FIGS. 1A and 1B are plan views of a ferromagnetic material layerand its magnetic structure;

[0032]FIG. 2 is a plan view of a ferromagnetic material layer of a TMRdevice according to a first embodiment of present invention;

[0033]FIG. 3 is a plan view of a ferromagnetic layer with an arrowindicating its magnetization direction according to a second embodimentof the present invention;

[0034]FIG. 4 is a magnetization hysteresis diagram of themagnetoresistance effect device according to the second embodiment ofthe present invention;

[0035] FIGS. 5A-5F are plan views showing a process of magnetizationinversion a ferromagnetic material layer of a magnetoresistance effectdevice according to the second embodiment of the present invention;

[0036]FIG. 6 is a diagram comparing a coercive force of theferromagnetic material layer of the magnetoresistance effect deviceaccording to the second embodiment of the present invention withcoercive forces of other devices having various shapes;

[0037]FIG. 7A is a view of a ferromagnetic material layer of acomparative example with an arrow indicating its magnetizationdirection;

[0038]FIG. 7B is a plan view of a magnetoresistance effect device withan arrow indicating its magnetization direction according to a thirdembodiment of the present invention;

[0039]FIG. 8 is a magnetization hysteresis diagram of amagnetoresistance effect device according to a third embodiment of thepresent invention;

[0040]FIGS. 9A and 9B are cross-sectional views of magnetoresistanceeffect devices according to a fourth embodiment of the presentinvention;

[0041]FIG. 10 is a cross-sectional view of a magnetoresistance effectdevice according to a fifth embodiment of the present invention;

[0042]FIG. 11 is a cross-sectional view of a magnetoresistance effectdevice according to a sixth embodiment of the present invention;

[0043]FIG. 12 is a cross-sectional view of a magnetoresistance effectdevice according to a seventh embodiment of the present invention;

[0044]FIG. 13 is a diagram comparing a coercive force of memory films ofvarious shapes;

[0045]FIG. 14 is a plan view of mask patterns of a manufacturing methodof a magnetoresistance effect device according to an eighth embodimentof the present invention;

[0046]FIGS. 15A and 15B are a cross-sectional view and a plan view forexplaining a method of manufacturing a magnetoresistance effect deviceaccording to a ninth embodiment of the present invention;

[0047]FIGS. 16A and 16B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 15A and 15B;

[0048]FIGS. 17A and 17B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 16A and 16B;

[0049]FIGS. 18A and 18B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 17A and 17B;

[0050]FIGS. 19A and 19B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 18A and 18B;

[0051]FIGS. 20A and 20B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 19A and 19B;

[0052]FIGS. 21A and 21B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 20A and 20B;

[0053]FIGS. 22A and 22B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 21A and 21B;

[0054]FIGS. 23A and 23B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 22A and 22B;

[0055]FIGS. 24A and 24B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 23A and 23B;

[0056]FIGS. 25A and 25B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 24A and 24B;

[0057]FIGS. 26A and 26B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 25A and 25B;

[0058]FIGS. 27A and 27B are a cross-sectional view and a plan view forexplaining a manufacturing method of a magnetoresistance effect deviceaccording to a tenth embodiment of the present invention;

[0059]FIGS. 28A and 28B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 27A and 27B;

[0060]FIGS. 29A and 29B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 28A and 28B;

[0061]FIGS. 30A and 30B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 29A and 29B;

[0062]FIGS. 31A and 31B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 30A and 30B;

[0063]FIGS. 32A and 32B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 31A and 31B;

[0064]FIGS. 33A and 33B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 32A and 32B;

[0065]FIGS. 34A and 34B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 33A and 33B;

[0066]FIGS. 35A and 35B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 34A and 34B;

[0067]FIGS. 36A and 36B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 35A and 35B;

[0068]FIGS. 37A and 37B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 36A and 36B;

[0069]FIGS. 38A and 38B are a cross-sectional view and a plan view forexplaining a manufacturing step after the steps in FIGS. 37A and 37B;

[0070]FIG. 39 is a plan view for explaining a manufacturing method of amagnetoresistance effect device according to an eleventh embodiment ofthe present invention;

[0071]FIG. 40 is a plan view for explaining a method of fabricating amagnetoresistance effect device according to a twelfth embodiment of thepresent invention;

[0072]FIG. 41 is a cross-sectional view showing a structure of one cellof MRAM according to a thirteenth embodiment of the present invention;

[0073]FIG. 42 is a circuit diagram of a MRAM according to the thirteenthembodiment of the present invention;

[0074]FIG. 43 is an overview of a magnetoresistance effect headaccording to a fourteenth embodiment of the present invention; and

[0075]FIG. 44 is an overview of a magnetic reproducing apparatus using amagnetoresistance effect head according to a fifteenth embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0076] According to an embodiment of the present invention, the physicalshape of at least one ferromagnetic material layer is controlled so theferromagnetic material layer has a particular magnetic structure that isappropriate for reducing a switching magnetic field by utilizingmagnetic edge domains. According to the embodiment of the presentinvention, edge regions of the ferromagnetic material layer each havingthe magnetic edge domains are not removed so as to form a parallelogram.Rather, the edge domains are extended by a certain size as describedbelow to promote or utilize its characteristic as a nucleus ofmagnetization inversion or magnetization change.

[0077] Turning now to FIG. 2, which is a plan view of a ferromagneticlayer 20 according to a first embodiment of the present invention. Asshown, the ferromagnetic layer 20 has a plane shape and includes acenter portion formed between two end portions so as to align with eachother. Each of the end portions has a width wider than the centerportion, and has an extended additional portion. Further, each of theextended portions of the ferromagnetic layer can be thought of as beingadded to a rectangular-shaped ferromagnetic layer. Further, each of theextended portions are substantially symmetrical aligned to each otherwith a substantial center point (x) of the ferromagnetic material layer20 as a pivot. Although each of the extended additional portions in FIG.2 are substantially symmetrical aligned with the substantial centerpoint (x) as the pivot, a precise adjustment of their symmetry andproportional breadth is not required and both extended portions may beunsymmetrical and have different breadths from each other. In addition,the plane shape shown in FIG. 2 is not symmetric to the straight line inFIG. 2 indicating an easy magnetization axis of the ferromagnetic layer20. In the ferromagnetic layer 20 of the above-described shape, anS-shape magnetic domain structure is formed and stabilized, whereby theswitching magnetic field is substantially reduced.

[0078] The above-described plane shape may also be applied to amulti-layered memory film including a plurality of ferromagnetic layersto reduce the switching field.

[0079] Turning now to FIG. 3, which is a plan view of a ferromagneticlayer including arrows for indicating a magnetization of theferromagnetic layer according to a second embodiment of the presentinvention.

[0080] As shown, the ferromagnetic layer 30 has hooked-portions 32 and33 at end portions to form an S-like shape. Further, the widths of thehooked-portions are different from a width of the center portion 31. Thecenter portion 31 has a continuous width of 0.1 μm and each end portion32 and 33 has a width of 0.15 μm. The layer 30 also has a length of 0.4μm and an average thickness of 1.5 μm.

[0081] The widths of the two end portions can be different from eachother. The magnetization free layer or film receives a stray magneticfield of the magnetization pinned layer, whereby its magnetizationhysteresis under a one-directional magnetic field that is in parallel tothe longer axis of the magnetization free layer may be different fromits magnetization hysteresis under another magnetic field that is inanti-parallel relation to the one-directional magnetic field. Thedifference in widths of the two end portions may reduce an effect of thedifference in magnetization hysteresis and equalize the magnetizationfree layer's coercive forces in two directions.

[0082] Although the shape of FIG. 3 is polygonal in which the respectivecorners are provided with an angle of 90 degrees, the angle of eachcorner is not limited to 90 degrees and the respective sides are notnecessarily limited to straight lines but may have curved lines. Thedevice size is also not limited to the above-described size, anddepending on a degree of integration, a maximum width of the layer 30may be preferably smaller than about 1 μm and the length of the layer 30may be preferably 1 through 10 times as large as the maximum width. Theaverage thickness of the ferromagnetic material layer is also preferablyequal to or smaller than 10 nm and more preferably equal to or smallerthan 5 nm.

[0083] The magnetic material for the ferromagnetic layer 30 may be oneof the normally used magnetic materials such as Fe, Co, Ni, an alloy,such as Co₉Fe, or the equivalents. A laminated film including a layer ofthe material can also be used in place of the ferromagnetic layer 30.The ferromagnetic layer 30 may also be substituted with a laminated filmincluding a nonmagnetic material layer including Cu, Au, Ru, Al or theirequivalents.

[0084] Next, FIG. 4 is a diagram illustrating results of a magnetizationhysteresis of the ferromagnetic layer 30 of Co₉Fe. The center portion 31of the layer 30 had a width of 0.1 μm and each of the end portions had awidth of 0.15 μm. Further, a length of the layer 30 was 0.4 μm and athickness was 1.5 nm. The coercive force Hc was calculated as 242 (Oe)from the hysteresis of FIG. 4 and a difference between the switchingmagnetic fields Hsw and the coercive force Hc is not so large that nosmall magnetic domains are produced, even with the complicated planeshape of the layer 30. Thus, the magnetization inversion procedure issmoothly processed.

[0085] The above-described plane shape can also be applied to amulti-layered memory film including a ferromagnetic layer, for reducingthe switching field of the multi-layered memory film.

[0086] Turning next to FIGS. 5A-5F, which are plan views of theferromagnetic material layer illustrating the magnetization changeaccording to the second embodiment of the invention.

[0087]FIG. 5A corresponds to an applied magnetic field H of +1000 (Oe)directed from right to left in the drawing. As shown, the magnetizationof the ferromagnetic material layer 30 is aligned with the appliedmagnetic field and the layer's easy magnetization axis. FIG. 5Bcorresponds to an applied magnetic field of +300 (Oe) directed fromright to left in the drawing and has a magnetization as shown by thearrows in FIG. 5B. As shown, when the applied magnetic field H is +300(Oe), the magnetization directions of the hooked-portions 32 and 33begin to change from the easy magnetization axis. FIG. 5C corresponds toa zero applied magnetic field, and as shown a stable magnetic domainstructure having an S-shape is formed in the ferromagnetic layer 30.

[0088] Further, FIG. 5D corresponds to an applied magnetic field of −200(Oe) directed from left to right. As shown, the magnetization directionof the ferromagnetic layer 30 is significantly rotated at the endportions of the wider width. FIG. 5E corresponds to an applied magneticfield of −300 (Oe) directed from left to right. As shown, themagnetization of the ferromagnetic layer 30 is substantially inverted.Also, FIG. 5F corresponds to an applied magnetic field of −1000 (Oe)directed from left to right. As shown, the magnetization of theferromagnetic layer 30 is completely inverted, and is directed from leftto right in alignment with the easy magnetization axis.

[0089] In magnetization inversion, the edge domains are enlarged whiletwo domain walls between each of the edge domains and the centermagnetic domain move in the direction toward the center of the layer.Therefore, complicated domain structures are not formed through theentire magnetization inversion and smooth magnetization inversion of asmall switching magnetic field is attained.

[0090] Because of the presence of the edge domains, a rate of residualmagnetization to saturation magnetization is 0.86. Generally, when thereis a disturbance in a magnetization direction of a ferromagnetic layerand the rate of residual magnetization to saturation magnetization issmaller than 1, a ferromagnetic tunnel junction may have a reducedtunnel MR amplitude compared to a tunnel junction in which themagnetization of ferromagnetic layer has no disturbance. When theferromagnetic tunnel junction including the two ferromagnetic layerswith a nonmagnetic dielectric layer deposited therebetween is formed inthe same shape, the two ferromagnetic layers tend to have asubstantially similar or high symmetry magnetic domain structures.Therefore, although the rate of the residual magnetization to thesaturation magnetization is smaller than 1, the tunnel magnetoresistanceis hardly reduced.

[0091] Next, FIG. 6 is a diagram illustrating a relationship betweenseveral plane shapes (a)-(g) of a ferromagnetic layer and theirrespective coercive forces Hc (Oe). The coercive forces of the sevenferromagnetic layers were calculated when the layer had a thickness of2.0 nm, a length of 0.4 μm, a width of the center portion of 0.1 μm.Further, a width of the end portions was 0.15 μm for the plane shapes(f) and (g).

[0092] As shown, the ferromagnetic layer having the least coercive forcehas the shape (g). The coercive force of the plane shape (b) which hastwo diagonally opposed cut-off corners from a rectangular shape is alsolow for the same reason as the parallelogram-shaped ferromagnetic layer.

[0093]FIG. 7A is a plan view of a parallelogram-shaped ferromagneticlayer 70 with arrows indicating the magnetic domain structure. In theparallelogram-shaped ferromagnetic layer 70, a magnetization of onlysmall portions 71 and 72 along an oblique side is directed in adirection different from an easy magnetization axis to which themagnetization of the center portion is aligned. The total magnetizationof the edge domains is less than the conventional rectangular-shapedferromagnetic layer 11 in FIGS. 1A and 1B, but is more than theferromagnetic layer 30 in FIG. 3.

[0094] Now, FIG. 7B is a plan view of a ferromagnetic layer of amagnetoresistance effect device according to a third embodiment of thepresent invention.

[0095] As shown, the ferromagnetic layer 75 has semicircle-shapedextended portions 76 and 77. Further, the semicircle-shaped extendedportions 76 and 77 have a gradually changing magnetization as indicatedby the arrows in FIG. 7B. The layer's magnetic domains were calculatedfor a ferromagnetic material of Co₉Fe. Other magnetic materials such asFe, Co, Ni, or their alloys and a laminated film of the ferromagneticmaterial layers can also be used. The laminated film may also have anonmagnetic metal layer including Cu, Au, Ru, Al or the equivalents.

[0096]FIG. 8 is a diagram of a calculated magnetization curve of theferromagnetic layer in FIG. 7B according to the third embodiment of thepresent invention. As shown, the coercive force Hc was as low as 148(Oe) and a rate of residual magnetization to saturation magnetizationwas as high as 0.96. A similar effect may also be obtained with amulti-laminated film which includes at least two ferromagnetic layersand at least a nonmagnetic dielectric layer and/or a nonmagnetic metallayer interposed between the two ferromagnetic layers.

[0097] Turning now to FIGS. 9A and 9B, which are sectional views ofmagnetoresistance effect devices 90 and 90′ according to a fourthembodiment of the present invention.

[0098] As shown, the magnetoresistance effect device 90 includes aferromagnetic single tunnel junction formed with a first ferromagneticlayer 91, a second ferromagnetic layer 93, and a nonmagnetic dielectriclayer 92 interposed between the two ferromagnetic layers 91 and 93. Inthis structure, at least one of the first and second ferromagneticlayers is a memory layer and its magnetization rotates in an appliedfield. By adopting the above-described plane shape to at least thememory layer of the device, the device can also attain a small coerciveforce. The plane shape can also be applied to all layers of the device.

[0099] A spin valve magnetoresistance effect element can also beobtained by forming an antiferromagnetic layer on either one of thefirst or second ferromagnetic layers 91 and 93 so as to fix themagnetization of the ferromagnetic layer adjacent to theantiferromagnetic material layer by antiferromagnetic exchange couplingthe ferromagnetic layer and the antiferromagnetic layer, whereby themagnetization fixed ferromagnetic layer is a magnetization fixed layer(a reference layer).

[0100] The magnetoresistance effect device of FIG. 9B has athree-layered film including two ferromagnetic material layers 91-1 and91-2 with a nonmagnetic metal layer 96 disposed therebetween in place ofthe first ferromagnetic layer 91 in FIG. 9A. The three-layered film canalso be used in place of the ferromagnetic layer 93. The multi-layeredfilm of three or larger number laminated of ferromagnetic layers andnonmagnetic layers can also be used as the first and the secondferromagnetic layers. The above-described plane shape can be adapted toat least of the ferromagnetic layers of the memory layer.

[0101] Further, each of the ferromagnetic layers 91 and 93 in FIG. 9A,91-1 and 93 in FIG. 9B can be used as an electrode coupled to lines,such as a bit line and word line for providing a sense current.

[0102] Next, FIG. 10 is a sectional view of a magnetoresistance effectdevice 100 according to a fifth embodiment of the present invention.

[0103] As shown, a first ferromagnetic layer 111 and a secondferromagnetic layer 113 are laminated with a first nonmagneticdielectric layer 112 disposed therebetween. The device also has a secondnonmagnetic dielectric layer 114 formed on the second ferromagneticlayer 113 and a third ferromagnetic layer 115 with a second nonmagneticdielectric layer 114 interposed therebetween.

[0104] The laminated structure of the magnetoresistance effect device100 may have a small coercive force by adopting the plane shape of thefirst through the third embodiments to at least one of the ferromagneticmemory layers. A spin valve TMR device can also be formed withantiferromagnetic layers each formed on the first and the thirdferromagnetic layers 111 and 115 so the ferromagnetic layers becomemagnetization fixed reference layers. Further, each of the ferromagneticlayers 111 and 115 can be used as an electrode coupled to sense currentlines, such as a bit line and word line.

[0105] Next, FIG. 11 is a sectional view of a magnetoresistance effectdevice 130 according to a sixth embodiment of the present invention.

[0106] As shown, the magnetoresistance effect device 130 has athree-layered film, in which two ferromagnetic layers 111-1 and 111-2sandwich a nonmagnetic metal layer 116, in place of the ferromagneticlayer 111 in FIG. 10. The three-layered film forms an antiferromagneticcoupling memory layer with the nonmagnetic metal layer 116 as anantiferromagnetic coupling layer.

[0107] Further, the antiferromagnetically coupling nonmagnetic metallayer 116 antiferromagnetically couples the two ferromagnetic layers111-1 and 111-2. The antiferromagnetic coupling three-layered film isdisclosed in Japanese Patent Laid-Open No. 09-25162, Japanese PatentApplication No. 09-263741 and U.S. Pat. No. 5,953,248, their entirecontents of which are incorporated by reference. The three-layered filmmay also be used in place of the third ferromagnetic layer 115. Themagnetoresistance effect device 130 with a small coercive force can beattained by using the above-described plane shape to at least one of theferromagnetic layers as a memory layer.

[0108]FIG. 12 is a cross sectional view of a magnetoresistance effectdevice 140 according to a seventh embodiment of the present invention.

[0109] As shown, the magnetoresistance effect device 140 has athree-layered film, in which ferromagnetic layers 113-1 and 113-2 arelaminated by interposing a nonmagnetic layer 117, in place of the secondferromagnetic layer 113 in FIG. 10. The three-layered film behaves as amemory film, where the magnetization of the two ferromagnetic layers113-1 and 113-2 invert or change while the two ferromagnetic layers113-1 and 113-2 are antiferromagnetically coupled with each other withthe nonmagnetic layer 117 as a metal coupling layer. Themagnetoresistance effect device 140 in FIG. 12 also has a small coerciveforce by adapting the plane shapes of the first through the thirdembodiments to the memory film. Either one of the first and the thirdferromagnetic layers 111 and 115 can also be replaced with thethree-layered film.

[0110] Next, FIG. 13 is a diagram of a relationship between severalplane shapes of a memory film and their respective coercive forces Hc(Oe). The memory film has the three-layered film of Co₉Fe ferromagneticlayer, Ru nonmagnetic metal layer and Co₉Fe ferromagnetic layer. The Runonmagnetic metal layer is a coupling layer for forming anantiferromagnetic coupling between the two ferromagnetic layers. Asshown, the coercive force can also be significantly reduced with theshapes (d) and (e) according to the embodiments of the present inventionin comparison with normal rectangular shapes.

[0111] A material of the ferromagnetic layer according to the respectiveembodiments of the present invention, is not particularly limited to theabove-described material, and Fe, Co, Ni, Fe alloy, Co alloy, Ni alloy,magnetite having a large spin polarizability, oxides ferromagneticmaterial, such as CrO₂, RXMnO_(3-y) (R: rare earth, X:Ca, Ba, Sr),Heusler alloys, such as NiMnSb and PtMnSb, magnetic semiconductors, suchas ZnMnO, TiMnO, CdMnP₂ and ZnMnP₂ and their equivalents can also beused.

[0112] A thickness of each ferromagnetic layer explained in therespective embodiments of the present invention is preferable in anappropriate range for preventing superparamagnetic characteristic of theferromagnetic material. It is preferable the thickness may be equal toor larger than 0.4 nm. When the thickness is excessively thick, theswitching magnetic field is enlarged. Therefore, it is preferable thethickness is equal to or smaller than 2.5 nm as an upper limit value. Anonmagnetic element, such as Ag, Cu, Au, Al, Mg, Si, Bi, Ta, B, C, O, N,Pd, Pt, Zr, Ir, W, Mo, Nb or their equivalents, may also be included inthe ferromagnetic layer, such that its ferromagnetic characteristic isnot lost as a whole. FeMn, PtMn, PtCrMn, NiMn, IrMn, NiO or theirequivalents can also be used for the antiferromagnetic film.

[0113] Cu, Au, Ru, Ir, Rh, Ag or their equivalents can be used for thenonmagnetic metal layer. The nonmagnetic layer as an antiferromagneticor ferromagnetic coupling layer includes the metal material. Thenonmagnetic coupling layer magnetically couples the two ferromagneticlayers stacked via the nonmagnetic coupling layer. When the magneticcoupling of the two ferromagnetic layers is antiferromagnetic coupling,the nonmagnetic coupling layer may include Ru, Ir, Rh, or theirequivalents. When the magnetic coupling between the two ferromagneticlayers is ferromagnetic coupling, the nonmagnetic material layer mayinclude Cu, Au, Ag or their equivalents. The three-layered filmutilizing ferromagnetic coupling is preferably used as the magneticmemory film and the three-layered film utilizing the antiferromagneticcoupling is preferably used as the reference layer, but they can be usedas both the memory layer and the reference layer.

[0114] For a dielectric layer or a nonmagnetic dielectric layer used inthe respective embodiments of the present invention, various dielectricmaterials can be used, such as Al₂O₃, SiO₂, MgO, AlN, AlON, GaO, Bi₂O₃,SrTiO₂, AlLaO₃ and their equivalents. The presence of oxygen or nitrogendeficiency of these dielectric layers is also permissible. A thicknessof the tunnel dielectric material layer is dependent on a junction areaof the TMR. It is preferable the thickness of the dielectric layer isequal to or smaller than 3 nm. The magnetoresistance effect device canalso be formed on various substrates of Si, SiO₂, Al₂O₃, AlN and theirequivalents. It is preferable to use a layer of Ta, Ti, Pt, Pd, Au ortheir equivalents, or a laminated film of Ti layer and Pt layer, Talayer and Pt layer, Ti layer and Pd layer, Ta layer and Pd layer ortheir equivalents between the substrate and lower surface of themagnetoresistance effect device, and/or to use at least one of them onan upper surface of the magnetoresistance effect device.

[0115] The above-described plane shapes including several conventionalshapes can also be formed by a process including coating a resist layerafter forming the layer(s), forming a resist pattern on the formedlayer(s) by applying light, an electron beam and an X ray onto theresist layer to form an exposed images, and by developing the exposedimage of the resist layer. The process also includes performing ionmilling or etching using the resist pattern as a mask pattern, therebyforming a single or a plurality of patterns. Further, the resist patternwill usually be exfoliated. Each step of the process can also bereplaced by its equivalent step or modified using different materials oremploying additional step(s).

[0116] When manufacturing magnetoresistance effect devices having arelatively large size, for example in a micron order, a mask pattern ofsilicon dioxide, silicon nitride or their equivalents for plurality ofthe magnetoresistance effect device patterns according to the presentinvention can be formed by using Reactive Ion Etching (RIE).

[0117] To form relatively small magnetoresistance effect devices of theabove-described shapes, for example from 0.1 μm through about 3 μm,photolithography can be used. In this case, a previously fabricated maskhaving a plurality of shapes of the magnetoresistance effect device ofthe embodiment of the present invention can be used, and etching can beperformed in accordance with the mask.

[0118] With regard to a device having a smaller size, for example about0.5 μm or smaller, EB exposure can be used. However, because the deviceis small per se, forming patterns of the magnetoresistance device withminute edge portions is more difficult.

[0119] To manufacture the device of such a small size, the electron beamcan be corrected. Normally, the correction of the electron beam is usedto form an appropriate pattern by correcting a proximity effect causedby back scattering of the electron beam at a surface of the substratesupporting the device. When forming a rectangular plane shape, anaccumulated charge amount at a vicinity of an apex is deficient and thefour corners of the rectangular shape become round. To make the cornerssubstantial right angles, the correction point beam is applied onto anouter side of the rectangular to increase the accumulated charge amountat the corners, especially for a device of about 0.5 μm or smaller. Thismethod can also be used in a manufacturing method of themagnetoresistance effect device of the present invention, as describedblow. For example, for forming the devices of FIGS. 3 or 7B, arectangular shape as a basic pattern is formed and an additionallyapplied correction beam at both diagonal corners can be used to form theend portions.

[0120] The appropriate plane shape in FIGS. 3 or 7B can be provided bymaking an impacted charge amount of the beam larger than normalproximity effect correction, and/or by adjusting a position of thecorrection point beam. To form the shape of the device in FIG. 7B, acorrection point beam may be irradiated on a plurality of points at theedge portions.

[0121] The correction beam for forming the end portions can also beimpacted after forming the device in the rectangular shape, however, itis necessary to realize a small rectangular shape of submicron order ata preceding stage.

[0122] Turning next to FIG. 14, which is a plan view of mask patterns ofa manufacturing method of a magnetoresistance effect device according toan eighth embodiment of the present invention. The eighth embodiment isfocused on a method of realizing the small rectangular shape of submicron order at a preceding stage.

[0123] When a rectangular shape is formed by a normal one-shotlithography, the corners of the rectangular are significantly lost whenone side of the rectangular is equal to or smaller than about 0.5 μm inphotolithography and equal to or smaller than about 0.2 μm in EBlithography. As a countermeasure against this problem, a proximityeffect correction against reflection of light in the photolithographyand proximity effect correction against back scattering of electrons inEB lithography have been studied. However, a problem with thiscountermeasure is the correcting operation needs additional time, and itis rather difficult to achieve a sufficient effect with the size ofabout 0.1 μm.

[0124] On the other hand, controlling a width of a linear pattern inlithography can accurately prescribe a width equal to or smaller than0.2 μm even in photolithography and a width equal to or smaller than 0.1μm in EB lithography. To form a desired rectangular pattern 151 (hatchedportion) in FIG. 14, a first linear pattern 152 is first formed bylithography so as to form a mask layer and the other region is removedby dry etching. A second linear pattern 153 is then formed bylithography to be orthogonal to the first linear pattern to form a mask,and a remaining region outside of the rectangle is removed by dryetching. Thus, a sharp pattern can be formed at the corner 154 of therectangular pattern.

[0125] Magnetoresistance effect devices having various shapes can alsobe formed by modifying the method in FIG. 14, as described in thefollowing embodiments.

[0126] FIGS. 15A-26B are views for explaining a method of manufacturinga magnetoresistance effect device according to a ninth embodiment of thepresent invention. Although these figures show one pattern of themagnetoresistance effect device, the manufacturing method for anintegrated memory apparatus may include forming a plurality of the samemagnetoresistance effect devices on one substrate. Further, the methodfor the integrated memory apparatus can be achieved in reference to thefollowing explanation. The method of manufacturing can form a MagneticTunnel Junction (MTJ) of a TMR device with sharp corners by repeatingthe linear pattern formation and etching.

[0127]FIG. 15A is a cross-sectional view along with the line 15A-15A ofa plan view of FIG. 15B. As shown, a wiring 162 of Ta, a MTJ film 163which includes a ferromagnetic layer, a nonmagnetic dielectric layer anda ferromagnetic layer, and a contact layer 164 of Ta are formed on amain surface of a Si substrate 161. A region 165 surrounded by abroken-line corresponds to a pattern where the MTJ of the TMR device isgoing to be formed. The MTJ film may also include ferromagnetic materialparticles and/or a multi-layered film including a ferromagnetic materialin place of the ferromagnetic layer(s).

[0128]FIG. 16A is a cross-sectional view along a line 16A-16A of a planview of FIG. 16B for explaining a manufacturing step following FIGS. 15Aand 15B. A pattern of the wiring 162 is formed by photolithography, anda pattern of the wiring 162, the MTJ film and the contact layer 164 areformed by etching using RIE in a presence of a mixture gas of C1 ₂ andAr using a resist (not illustrated), formed by photolithography, as amask.

[0129]FIG. 17A is a cross-sectional view along a line 17A-17A of a planview of FIG. 17B for explaining a manufacturing step following FIGS. 16Aand 16B. Side surfaces of the pattern of wiring 162, the MTJ film 163and the contact layer 164 are surrounded with a nonmagnetic dielectriclayer 166 of SiO_(x), and the surfaces of the contact layer 164 and thenonmagnetic dielectric layer 166 of SiO_(x) are flattened by a ChemicalMechanical Polishing (CMP) or an etch-back process.

[0130]FIG. 18A is a cross-sectional view along a line 18A-18A of a planview of FIG. 18B for explaining a manufacturing step following FIGS. 17Aand 17B. The first linear resist pattern 167 is formed to extend longerthan a length of the intended junction region 165. Further, a width ofthe first linear pattern 167 defines a minimum dimension of shorter axisof the TMR junction. When the width is about 0.1 μm, the width can becontrolled by photolithography. When the width is less than 0.1 μm, itis preferable to use EB lithography.

[0131]FIG. 19A is a cross-sectional view along a line 19A-19A of a planview of FIG. 19B for explaining a manufacturing step following FIGS. 18Aand 18B. The linear resist pattern 167 is transcribed to the contactlayer 164 using RIE, and thereafter the resist 167 is removed. Areactive gas of F species, for example SF₆, can be used during the RIEand the linear pattern of the resist 167 can be accurately transcribedto the contact layer 164 of Ta and adjacent portion of SiO_(x) layer166. The magnetic metal layer of the MTJ film 163 is provided with aresistance against dry etching of the F species gas, whereby only thecontact layer 164 of Ta is formed into the linear pattern.

[0132]FIG. 20A is a cross-sectional view along a line 20A-20A of a planview of FIG. 20B for explaining a manufacturing step following FIGS. 19Aand 19B. The matrix of the MTJ film 163 is subjected to ion milling withthe contact layer 164 of Ta as a mask, where Ta is provided with asufficient resistance as a hard mask against ion milling. Therefore,even when Ar ion milling having a beam energy of 400 (eV) is performedto expose the wiring layer 162 of Ta, a recess of the Ta mask layer 164and reduction of the film thickness of layer 161 are inconsiderable andthe fine linear pattern of the contact layer 164 of Ta can betranscribed to the MTJ film 163. Reactive dry etching using a mixturegas of Cl₂ and Ar can also be used to make the pattern of the MTJ film163 in place of the ion milling. Materials excellent in Cl speciesetching resistance, such as Diamond Like Carbon (DLC), AlO_(x), SiO₂, amulti-layered resist mask or their equivalents can also be used as themask layer. The insulating film 166 etched simultaneously can be amaterial which has reduced etching resistance against Cl species, suchas TEOS. It is preferable to previously form a mask layer on the contactlayer 164.

[0133]FIG. 21A is a cross-sectional view along a line 21A-21A of a planview of FIG. 21B for explaining a manufacturing step following FIGS. 20Aand 20B. The nonmagnetic dielectric layer 166′ of SiO_(x) is formed soas to surround the contact layer 164 on the MTJ film 163 and thesurfaces of the nonmagnetic dielectric layer 166′ and the contact layer164 are flattened. A wide pattern indicated by broken lines of FIG. 21Bcorresponds to the embedded wiring layer 162.

[0134]FIG. 22A is a cross-sectional view along a line 22A-22A of a planview of FIG. 22B for explaining a manufacturing step following FIGS. 21Aand 21B. A resist 168 of FIGS. 22A and 22B for prescribing the two otherremaining sides of the TMR junction 165 and having a second linearpattern sufficiently longer than the intended junction pattern is formedby photolithography.

[0135]FIG. 23A is a cross-sectional view along the line 23A-23A of aplan view of FIG. 23B for explaining a manufacturing step followingFIGS. 22A and 22B. The second linear pattern by the resist 168 istranscribed to the contact layer 164 of Ta by dry etching using areactive gas of F species and then the resist 168 is removed, wherebythe contact layer 164 aligned to the intended pattern 165 is formed.

[0136]FIG. 24A is a cross-sectional view along the line 24A-24A of aplan view of FIG. 24B. The MTJ film 163 and the wiring layer 162 of Taare etched using the contact layer 164 as a hard mask by ion milling.The MTJ film 163 is formed to have a final shape of predeterminedpattern 165, whereby the rectangular shape of the ferromagnetic tunneljunction is formed while maintaining the sharpness of the corners.

[0137] The contact layer 164 of the embodiment is used as a mask andtherefore it has the same shape as the MTJ film. However, the contactlayer 164 does not necessarily have the same plane shape and can have alarger or smaller plane shape than the predetermined shape 165 formed bysuccessive process.

[0138] The second linear pattern of resist 168 can be alternativelyformed to be inclined from the orthogonal relation with the resist 168to the first linear pattern of the MTJ film 163 of FIG. 22B, whereby aMTJ of a parallelogram of a low coercive force characteristic is formed.

[0139]FIG. 25A is a cross-sectional view along a line 25A-25B of a planview of FIG. 25A. The SiO_(x) insulating film 166′ is formed to surroundthe side surfaces of the MTJ film 163 and the contact layer 164 and itssurface is flattened with the surface of the contact layer 164 of FIGS.25A and 25B.

[0140]FIG. 26A is a cross-sectional view along a line 26A-26A of a planview of FIG. 26B. A wiring layer 169 having a multi-layered film,including Ti layer, TiN layer, AlCu layer and Ti layer, is formed on theflattened surface of the contact layer 164 and the SiO_(x) insulatingfilm 166′ and is patterned by photolithography and dry etching, therebythe wiring layer 169 coupled to the TMR device 163 is formed and the TMRdevice with an peripheral circuit (not shown) is electrically connected.

[0141] The wiring layer 169 can be alternatively formed over the contactlayer 164 and SiO_(x) insulating film 166′ following the step of FIGS.21A and 21B. Also, the second linear mask pattern 168 can be formed tomake a pattern of the wiring layer 169 as well as the ferromagnetictunnel junction 165. This process step configuration has an advantage ofdispensing with the independent lithography process for forming thewiring layer 169.

[0142] FIGS. 27A-38B are views for explaining a manufacturing method ofa magnetoresistance effect device according to a tenth embodiment of thepresent invention.

[0143] Manufacturing steps relating to FIGS. 27A, 27B, 28A, 28B, 29A and29B can be processed in similar way to the above-described steps ofFIGS. 15A, 15B, 16A, 16B, 17A and 17B. Therefore, a duplicateexplanation thereof is omitted. FIG. 27A is a cross-sectional view alonga line 27A-27A of a plan view of FIG. 27B, FIG. 28A is a cross-sectionalview along a line 28A-28A of a plan view of FIG. 28B, and FIG. 29A is across-sectional view of a line 29A-29A of a plan view of FIG. 29B.Numeral 171 corresponds to the Si substrate 161, numeral 172 correspondsto the wiring layer 162 of Ta, numeral 173 corresponds to the magnetictunnel junction (MTJ) layer 163, numeral 174 corresponds to the contactlayer 164 of Ta, and numeral 175 corresponds to a predetermined regionfor the TMR device including predetermined intended region 165 of MTJ.

[0144]FIG. 30A is a cross-sectional view along a line 30A-30A of a planview of FIG. 30B. A layer 177 of Cr is formed over the surfaces of thecontact layer 174 and the SiO_(x) insulating film 176. A wide patternindicated by broken-lines in FIG. 30B corresponds the pattern of thecontact layer 174.

[0145]FIG. 31A is a cross-sectional view along a line 31A-31A of a planview of FIG. 31B. A resist 178 for a first linear pattern is formed byphotolithography. The first linear pattern by the resist 178 istranscribed to Cr mask layer 177 using dry etching in a presence of amixture gas of Cl₂ and O₂.

[0146]FIG. 32A is a cross-sectional view along a line 32A-32A of a planview of FIG. 32B. The resist 178 is removed and the mask layer 177 of Cris remained. The mask layer 177 is thin enough so the dry etching formaking pattern of the Cr mask layer 177 does not substantially affect asurface flatness of the layer 174 of Ta and the SiO_(x) insulating film176.

[0147]FIG. 33A is a cross-sectional view along a line 33A-33A of a planview of FIG. 33B. A resist 179 for a second linear pattern is formed byphotolithography to be orthogonal to the first linear patterntranscribed to the Cr mask layer 177.

[0148]FIG. 34A is a cross-sectional view along a line 34A-34A of a planview of FIG. 34B. The resist pattern 179 is transcribed to a pattern ofthe Cr mask layer 177 using dry etching in a presence of a mixture gasof C1 ₂ and O₂. The Cr mask layer 177 is patterned to have sharp cornersand to correspond to a final shape of the ferromagnetic tunnel junction175. Because of the dry etching selective ratio of the Cr mask layer 177and the Ta contact layer 174 is large enough that the film thickness ofthe Cr mask layer 177 can be about 20 nm, whereby no dent of substantialdepth is formed on the surface of the SiO_(x) insulating film 176.

[0149]FIG. 35A is a cross-sectional view along a line 35A-35A of a planview of FIG. 35B. Using the rectangular mask pattern of the Cr masklayer 177 by dry etching in a presence of SF₆ forms the contact layer174 of Ta.

[0150]FIG. 36A is a cross-sectional view along a line 36A-36A of a planview of FIG. 36B. The MTJ film 173 is etched and the wiring layer 172 ofTa is exposed to Ar ion milling using the Ta contact layer 174 as amask. The pattern of the MTJ film 173 can also be formed by a reactivedry etching in a presence of a mixture gas of C1 ₂ and Ar in place of Arion milling.

[0151]FIG. 37A is a cross-sectional view along the line 37A-37A of aplan view of FIG. 37B. An SiO_(x) nonmagnetic dielectric layer 176′ isformed around the side surface of the MTJ film 173 and the contact layer174, and the surfaces of the SiO_(x) nonmagnetic dielectric layer 176′and the contact layer 174 are flattened by CMP.

[0152]FIG. 38A is a cross-sectional view along a line 38A-38A of a planview of FIG. 38B. A wiring layer 180 is formed using a known method andthe TMR device is coupled to a peripheral circuit (not shown) via thewiring layer 180. Several successive steps known in the art may beemployed after the above-described steps to complete the manufacturingof the magnetic memory apparatus.

[0153] As the mask layer for forming the pattern of MTJ film, DLC or anonphotosensitive organic material, such as polyimide or itsequivalents, can be used. When these materials are used as the masklayer, dry etching using an O₂ gas as a reactant, can be employed,whereby the etching selective ratio of the mask layer to the metalcontact layer 174 becomes large enough so a deterioration of the metalcontact layer 174 can be eliminated. In that case, an O₂ plasmaresistant process on a resist surface, such as silylation, ormulti-layered resist in photolithography is preferably used. Because DLCor a nonphotosensitive organic material is amorphous, a very smoothsidewall is provided even when forming a very small pattern of 0.1 μmorders.

[0154] A pattern of MTJ film of a lower coercive force characteristiccan be formed by repeating a linear pattern formation and dry etchingthree times.

[0155] As is known from the diagram of FIG. 6, the shape (b), in whichthe diagonal corners are cut, can also attain a comparatively lowcoercive force characteristic. The shape (b) of FIG. 6 can be providedas a ferromagnetic tunnel junction 181 of a hatched portion by repeatinga formation of linear patterns 182, 183 and 184 of a plan view in FIG.39, and dry etching each time. By repeating the linear pattern formationand etching a plurality of times, a junction pattern of a convexpolygonal shape can be accurately formed.

[0156] It is clear that such a process of linear pattern formation anddry etching a plurality of times, is applicable to both of the method ofetching up to the ferromagnetic tunnel junction by the linear patternsas in the ninth embodiment and the method of etching only the mask layerby the linear pattern as in the tenth embodiment.

[0157] When the above-described method for forming the multiple linearpatterns is used in forming a plurality of TMR devices aligned in crosspoints of lattice in an integrated memory apparatus, lithography isefficient.

[0158]FIG. 40 is a plan view for explaining a manufacturing process ofthe TMR device of FIG. 7B according to a twelfth embodiment of thepresent invention. A first linear pattern 192 is first formed byphotolithography, and patterns 193 of a semicircular shape are added tobe aligned at diagonal corners of a rectangle by spot EB drawing. Achemically sensitized resist for EB and/or far ultraviolet beam, such asSAL 601, can be used as a resist. The linear pattern with theprojections 193 in a semispherical shape can also be formed by a methodof mix and match for performing photolithography and EB lithography withan overlap.

[0159] Generally, EB lithography is a process having a low processthroughput, but only the pattern having a diameter of 50 nm can be drawnat a very high speed by the spot drawing. For example, when the spotdrawing is performed by a beam current of 100 pA using the chemicallysensitized SAL601 resist, about 10⁹ pieces of spots in correspondencewith a memory capacity of 1 Gbit can be drawn only in several minutes.Therefore, MRAM in correspondence with 1 Gbit can be fabricated withhigh productivity by combining a linear pattern exposure having a widthof about 0.1 μm by photolithography and spot exposure having a diameterof about 50 nm by EB lithography.

[0160] The above-described ferromagnetic tunnel junction is applicableto a magnetic recording apparatus, a magnetoresistance effect head, amagnetic reproducing apparatus or their equivalents.

[0161]FIG. 41 is a cross-sectional view of a part of a magnetic memoryapparatus according to a thirteenth embodiment.

[0162] As shown, the MOSFET 220 includes a gate electrode 222 and sourceand drain regions 223 and 224. The gate electrode 222 is formed on thesemiconductor substrate 221 via a gate insulator layer and the sourceand drain regions 223 and 224 is formed in the surface of thesemiconductor substrate 221. The gate electrode 222 extends in adirection orthogonal to a paper surface of FIG. 41 and forms a word lineWL1. A wiring 233 is coupled with one of the source drain regions 224via a contact 232 and is connected to a magnetoresistance effect device210 of any of the above-described embodiments of the present invention.The magnetoresistance effect devices 210 are coupled with the wiring 233and a bit line 234. A write line WL2 is formed near themagnetoresistance effect device 210 and the write line WL2 is used forwriting and inverting magnetization of ferromagnetic material layer ofthe magnetoresistance effect device 210 by a current flow, as themagnetization is magnetic information.

[0163] Memory apparatus, such as MRAM, are generally expected to have alarge capacity. Therefore, not only a wiring width but also an area ofeach cell is obliged to be reduced. The switching electric field can bereduced by using the magnetoresistance effect device according to thepresent invention and write current necessary for writing amagnetization invert may be reduced, whereby power consumption beingrestrained and switching being carried out at high speed.

[0164]FIG. 42 is a diagram of a part of magnetic random access memoryapparatus including the TMR device 210. The memory apparatus includes aplurality of word lines WL1 222, for selecting a memory cell to readmagnetic information of the selected memory cell, coupled to a rowdecoder 240 and a plurality of bit lines BL 234 coupled to a columndecoder 250. Each bit line BL 234 is intersected with each word line WL1222 and a plurality of the TMR devices 210 according the embodiments areformed at each of the intersections.

[0165] The MOSFET 220 for selecting a memory cell including the TMRdevice is formed to couple the TMR device 210 of each memory cell andits gate electrode is WL1 222, whereby the TMR device 210 of the memorycell can be selected by controlling the word line WL1 222. Each of theplural word lines WL2 231, for writing the magnetic information byinverting or changing the magnetization of the ferromagnetic materiallayer, extends in a direction in parallel with the word line WL1 222 andis near a magnetoresistance device 210.

[0166] Each of a plurality of diodes formed in place of the MOSFET 220can alternatively be used as switching transistor. Each of the diodesmay be formed on the word line WL1 222 at the intersection, the bit lineBL 234 may be formed on the TMR device 210 at the intersection, and theplurality of the memory cells are arranged in an array to form the MRAM.The MRAM can be mounted to a memory region of a mode terminal ofportable telephone, personal digital assistant.

[0167] A fourteenth embodiment is an embodiment in which themagnetoresistance effect device of the present invention is applied to amagnetic head.

[0168]FIG. 43 is an overview of a magnetoresistance head assemblymounted with the MR device according to the first through the seventhembodiments of the present invention. An actuator arm 301 is providedwith a hole for being fixed to a fixed shaft inside of a magnetic diskapparatus and is provided with a bobbin portion for holding a drive coil(not illustrated) and the like. A suspension 302 is fixed to one end ofthe actuator 301. A front end of the suspension 302 is wired with a leadwire 304 for writing and reading signals, one end of the lead wire 304is coupled with respective electrode of a magnetoresistance effectdevice 305 mounted on a head slider 303, and the other end of the leadwire 304 is connected to an electrode pad 306.

[0169]FIG. 44 is an overview of an inner structure of a magnetic diskapparatus (magnetic information reproducing apparatus) mounted with themagnetic head assembly of FIG. 43. A magnetic disk 311 is mounted on aspindle 312 and is rotated by a motor (not illustrated) responding to acontrol signal from a control portion of a drive apparatus (notillustrated).

[0170] The actuator arm 301 is fixed to a fixed shaft 313 for supportingthe suspension 302 and the head slider 303 at the front end thereof.When the magnetic disk 311 is rotated, a surface of the head slider 303opposed to the disk 311 is held in a floating state from a surface ofthe magnetic disk 311 by a predetermined amount, thereby reproducing themagnetic information of the magnetic disk. At another end of theactuator arm 301, a voice coil motor 314 is provided and includes a typeof a linear motor. The voice coil motor 314 includes a drive coil (notillustrated) wound up to the bobbin portion of the actuator arm 301 anda magnetic circuit including a permanent magnet and an opposed yokearranged to be opposed to each other to interpose the coil.

[0171] The actuator arm 301 is supported by ball bearings (notillustrated) provided at two upper and lower locations of the fixedshaft 313 and can freely be slidingly rotated by the voice coil motor314.

[0172] According to the magnetic head or the magnetic reproducingapparatus using the MR device of the embodiments of the presentinvention, operation at a speed faster than the conventional apparatusand a more stabilized and large capacity formation can be attained.

[0173] According to the magnetoresistance effect device of the presentinvention, the coercive force is small and the switching magnetic fieldis small. When the device is used as a memory cell of a magnetic memory,the current of a write wiring for generating a magnetic field necessaryfor inverting magnetization can be reduced. Therefore, according to themagnetic memory forming the memory cell by the magnetoresistance effectdevice of the present invention, a highly integrated formation can beperformed, the power consumption is reduced, and the switching speed canbe made faster.

[0174] Further, according to the method of fabricating themagnetoresistance effect device of the present invention, an easyprocess with excellent yield can be used to fabricate theabove-described device.

[0175] Although the present invention has been particularly shown anddescribed with reference to an embodiment thereof, it will be understoodthose skilled in the art that various other changes in the form anddetails may be made therein without departing from the spirit and scopeof the present invention.

1. A magnetoresistance effect device, comprising: a first ferromagneticlayer; a first nonmagnetic dielectric layer formed on the firstferromagnetic layer; and a second ferromagnetic layer formed on thefirst nonmagnetic dielectric layer, wherein one of the first and secondferromagnetic layers comprises a plane shape in which a center region isdisposed between first and second end regions, and the center region hasa width narrower than each width of the first and second end regions. 2.The magnetoresistance effect device according to claim 1, wherein thefirst nonmagnetic dielectric layer and the other of the first and secondferromagnetic layers has a plane shape aligned to the plane shape of theone of the first and second ferromagnetic layers.
 3. Themagnetoresistance effect device according to claim 1, wherein at leastone of the first and the second ferromagnetic layers comprises alaminate film including a pair of ferromagnetic layers, and anonmagnetic layer formed between the pair of ferromagnetic materiallayers.
 4. The magnetoresistance effect device according to claim 1,further comprising: a second nonmagnetic dielectric layer formed on thesecond ferromagnetic layer; and a third ferromagnetic layer formed onthe second nonmagnetic dielectric layer.
 5. The magnetoresistance effectdevice according to claim 1, wherein the first and second end regionsrespectively comprise a base region and a extended region, the centerregion and two base regions of the first and second end regionssubstantially form a rectangular, and the two extended regions are addedto the rectangular to be substantially aligned diagonally to each other.6. The magnetoresistance effect device according to claim 5, wherein therectangle has a shorter axis and a longer axis, the center region andtwo base regions are aligned to be substantially parallel to the longeraxis, and each of the two extended regions are extended from the baseregion in a direction orthogonal to the longer axis.
 7. Themagnetoresistance effect device according to claim 5, wherein the planeshape comprises an S-shape.
 8. The magnetoresistance effect deviceaccording to claim 5, wherein each of the two extended region has asubstantially semicircular-plane shape.
 9. The magnetoresistance effectdevice according to claim 1, wherein said one of the first and secondferromagnetic layers comprises a magnetization free layer in which amagnetization is free to rotate in an applied magnetic field.
 10. Themagnetoresistance effect device according to claim 9, wherein the otherof the first and second ferromagnetic layers comprises a magnetizationpinned layer in which a magnetization is fixed in the applied magneticfield.
 11. The magnetoresistance effect device according to claim 1,wherein the plane shape is substantially rotationally symmetrical with acenter of the plane as a pivot.
 12. The magnetoresistance effect deviceaccording to claim 11, wherein said one of the first and secondferromagnetic layers has an easy magnetization axis and the plane shapeis not substantially symmetrical with the easy magnetization axis. 13.The magnetoresistance effect device according to claim 1, wherein thewidths of the first and second end regions are different from eachother.
 14. A magnetic random access memory, comprising a plurality ofthe magnetoresistance effect devices of claim
 1. 15. A personal digitalassistance, comprising a plurality of the magnetoresistance effectdevices of claim
 1. 16. A magnetic reproducing head, comprising themagnetoresistance effect device of claim
 1. 17. A magnetic informationreproducing apparatus, comprising the magnetoresistance effect device ofclaim
 1. 18. A method of manufacturing a magnetoresistance effectdevice, comprising: forming a first ferromagnetic body, a nonmagneticdielectric layer on the first ferromagnetic body, and a secondferromagnetic body on the nonmagnetic dielectric layer; etching part ofan external region of a predetermined ferromagnetic tunnel junctionregion using a first liner mask pattern which is traversing thepredetermined ferromagnetic tunnel junction region; and etching anotherpart of the external region of the predetermined ferromagnetic tunneljunction region using a second liner mask pattern which is traversingthe predetermined ferromagnetic tunnel junction region and intersectingwith the first linear mask pattern.
 19. The method according to claim18, wherein the first and second linear mask patterns are substantiallyorthogonal to each other.
 20. The method according to claim 18, furthercomprising: forming a pair of extended regions using an electron beam,the pair of extended regions being positioned diagonal to each other.